1. Field of the Invention
The present invention relates to a door latch device.
2. Description of the Related Art
Generally, a door or the like of a vehicle is provided with a door latch device. The door latch device includes a striker which is provided on either one of a vehicle body and the door, and a fork (hook) and a pawl lever (ratchet) which is provided on the other. The fork is a member for grasping and releasing the striker, while the pawl lever is a member for holding the fork in a state where the striker is grasped by the fork. The fork is always urged in a direction of releasing the striker, and the door latch will be released by rotating or moving the pawl lever into a position not in mesh with the fork. The door is adapted to be closed or opened by employing such door latch device.
However, when the door is closed, striking sounds 1, 2 and 3 successively occur from the door latch device, as shown in FIG. 7. The striking sound 1 occurs when the striker strikes the fork, after the striker has entered into the latch. The striking sound 2 occurs when the pawl lever strikes the fork for locking the rotation of the fork so as to bring the door into a so-called half-latched state, after the striker has further entered to rotate the fork. The striking sound 3 occurs when the pawl lever strikes a rubber damper or the like for the purpose of finally locking the rotation of the fork so as to bring the door into a so-called full-latched state, after the striker has further entered to rotate the fork.
The above described striking sounds 1, 2, 3 will make passengers uncomfortable in some cases, and so, there has been proposed a door latch device for preventing occurrence of the striking sounds 1, 2, 3, as shown in FIG. 8, by applying a muffling structure to the striker, fork and pawl lever. The conventional door latch devices of this type are disclosed, for example, in JP-UM-B-6-524 and JP-UM-B-6-16002.
However, opening and closing speed of the door varies depending on each passenger, and the conventional door latch device has not been in compliance with such opening and closing speed of the door. Particularly, when the door is opened, the position of the pawl lever to be butted against the fork for engagement varies according to the closing speed of the door, and naturally, the striking sound will change. For this reason, a user may feel uneasy about locking the door, due to the change in the striking sound. Additionally, the conventional door latch device has been designed in such a manner that sound pressure level of the closing sound of the door may be reduced, for the purpose of enhancing quality of the vehicle. On the other hand, feeling of click has not been considered. Moreover, in recent years, some users have a great respect to quality of sound, tone of sound, volume level of sound, etc., and such requests have been more and more increased. Besides, it is not considered that improvement in quality of the vehicle can be achieved only by reducing the closing sound of the door.
Under the circumstances, the invention has been made in order to solve the above described problem, and an object of the invention is to provide a door latch device which stably generates a striking sound, even though a closing speed of a door has changed, and at the same time, to provide a door latch device which can impart an enhanced quality to a vehicle, by improving tone of the occurring sound, without lowering sound pressure, and such identity as different from other vehicles.